Pick
all the grumichamas/jaboticabas from the trees. Don't worry about
removing the stems or the frilly bits on the fruit where the flower
was. Wash the fruits, and then put them in a large pot and just
cover with water. Bring to the boil and simmer for at least half
an hour to an hour. Make sure the water doesn't evaporate. Add more
water if you need to, during the process. Once the fruit is really
soft, strain the juice.

[
Fancy cookbooks tell you to strain it through muslin and leave it
to drip for 24 hours and not to squeeze the juice through the muslin.
I just ignore this. I don't use muslin, just a strainer. You can
mash it and squeeze the fruit to get more juice out if you want
- it will mean the final product will be more cloudy.]

Measure the juice you have recovered - how many cupfuls? Then place
this juice into a jam pan, and add the equal number cups of sugar.
Add the juice of a few limes/lemons, and cook until the sugar has
dissolved. Add the jamsetter (amount depends on the quantity of
juice) and boil for at least five minutes. Test the jam by placing
a drip on a cold plate and when it wrinkles, the jam is cooked.
If it doesnt wrinkle after 10 minutes, add more jam setter.

Heat the jars and lids before you start in the oven for about 20
minutes. Pour liquid into the hot jars and put lids on as soon as
you can.